The present invention relates generally to a drive, particularly for a door mechanism, and more specifically to a drive having a sensor for the position of the driven parts, particularly doors.
When many parts are driven, different switching Processes must be triggered at different positions, just as in the case of driven doors, in order to accelerate or delay the respective driving movement or the like. In addition, the drive must stop when indicated end positions are reached.
For the mentioned switching processes of previous drives, different limit switches and sensors are mounted at different positions that must be indicated for a specific application. In the case of a door drive, for example, the mounting of a total of seven limit switches or sensors may be necessary that are actuated by door wings or parts connected with said door wings. This is considerably difficult, since the positions of the switches or sensors must be fixed in advance. An arrangement at a different point is time-consuming and costly.
In addition, drives for doors are known that, via auxiliary gears, are coupled with potentiometers. The resistance varies when the drive is moved and forms an analog signal for the position of the driven doors and parts.
Finally, it is known to arrange pulse generators driven by the drives that are coupled with counters or the like in order to form, from the number of received pulses, a signal for the position change of the driven doors and parts.
The above-described systems require improvements to the extent that they are costly with respect to manufacturing and work with parts that are subjected to a relative amount of wear. In the case of the pulse-generator/counter combination, the respective existing information concerning the momentary position of the driven parts is destroyed as a rule in the case of a power failure. Thus, when the power is switched on again, the system does not "know" where the driven parts are located.
It is therefore the objective of the invention to provide a drive, particularly a door drive, that operates with parts that are extremely free of wear and in any operational phase, completely irrespectively of the type of the preceding operational phases or breakdown periods, is able to generate a signal that reflects the respective position of the driven parts.
This objective is achieved by a driving element for a driven part that axially adjusts a softly magnetic core via a reducing gear relative to a concentric coil arrangement. The coil arrangement consisting at least of a primary coil that can be connected to an alternating voltage as well as of a secondary coil that has the same axis as the primary coil, at which a secondary voltage can be tapped that depends on the position of the core.
The secondary voltage therefore furnishes a signal for the actual position of the driven parts and not only a signal for their position changes. This signal will be immediately and directly available again after a power outage when the power supply is switched on again.
The electric circuit parts of the arrangement according to the invention are completely free of wear. In this case, it is a special advantage that the secondary voltage clearly changes even in the case of small changes of the position of the core. As a result, it is easily possible to couple the core at a high reduction with respect to the drive. Thus, a long path of travel of the doors and parts that are actuated by the drive corresponds to only a slight adjustment or movement of the core, which produces a clearly distinguishable secondary voltages. The arrangement according to the invention is therefore suitable for the monitoring of particularly long regulating distances.
Another special advantage of the invention is the fact that a change of the driving movements alone can take place by a correspondingly changed programming of a control or regulating circuit assigned to the drive, without a changed mounting of the core arrangement or of the core. This offers the possibility of being able to adapt the drive according to the invention without any mechanical changes to different usages.
According to a preferred embodiment of the invention, the reduction gear, which includes a threaded bushing and a threaded part, is arranged as the driving connection between a rotating part, such as a shaft, the drive and the core.
In a particularly preferred embodiment of the invention, the coil arrangement may in this case be arranged with the core inside an axial recess of a shaft or within a wheel of the drive. In this case, the shaft or the wheel may consist of a ferromagnetic material, such as steel or the like. This type of material is even desirable in view of an effective shielding of the coil arrangement toward the outside.
The arrangement of the coils and of the core within the shaft or the like, is such that the coil arrangement is held in the shaft or the like by a carrier shell which is fastened on the outside of one axial end of the shaft or the like at a housing of the drive. The core or a portion of said core a non-circular cross-section and is guided axially slidably, but non-rotatably in a guide bushing that is arranged at the free end of the carrier shell within the shaft or the like. Within the other end of the shaft or the like, a threaded bushing is arranged that does not rotate with respect to the shaft or the like and interacts with a threaded part that can be screwably slid in it is fixedly connected with the core. As a result, an extremely space-saving arrangement can be obtained.
The threaded part is biased by a spring in one axial direction, so that the threaded bushing and the threaded part can continuously interact with one another without play. In this case, the spring may be clamped under pressure between the threaded part and the guide bushing.
In the case of a unintended, extreme axial shifting of the threaded part, the spring disengages the threaded part and engages the threaded bushing, thereby relieving the threaded part from the pressure of the spring. At the same time, another spring can become effective and try to force the threaded part in the direction of the first spring. This arrangement has the advantage that the threaded part in extreme axial positions, when the threads of the threaded part and of the threaded bushing no longer engage, is forced by means of spring force into the direction of the threaded bush. Thus, when the shaft is rotated in the corresponding direction, is again screwed into the threaded bush.
The secondary voltage can be converted into different signals corresponding to the position of the driven doors or parts.
The secondary voltage, if necessary after a rectification or smoothing, can be fed to an evaluating circuit having a plurality of adjustable comparators set for differing levels of voltage to determine the differing positions of the driven parts from the output signals of the different comparators.
Alternatively, the secondary voltage, that may be smoothed and rectified, may also be fed to an analog-digital converter so that a digital signal is available for the momentary position of the driven parts.
As another alternative, the secondary voltage may be fed to an evaluating circuit that, generates an output voltage with a level that is an analog to the secondary voltage. As a result, a correspondingly changed current can be impressed on a resistor that is connected to the output. This current may be added to the consumption of the evaluating circuit for example, in that the evaluating circuit is, in series with a resistor, connected to a power supply system, and the mentioned output, via the resistor connected on the outlet side, is connected with a supply line of the evaluating circuit. In the case of this arrangement, a voltage that changes with the level of the output also changes across the resistor that is located in series with the evaluating circuit. The advantage of this arrangement is that the position of the driven doors or driven parts can be tapped away from the evaluating circuit via a supply line of the evaluating circuit, for example, by the determination of the voltage across the resistor that is arranged in series with the evaluating circuit. Thus, when the signals are processed away from the evaluating circuit, no separate measuring lines or the like are required in addition to the supply lines. In addition, it is advantageous that extremely high or low voltage drops occur across the resistor that is located in series with the evaluating circuit, when a short circuit is present in the evaluating circuit or a line breakage in the supply lines. As a result, it can be continuously checked whether the evaluating circuit works correctly or not.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.